IS IT A REAL POLLACK? HERE WE GO AGAIN.

On one side stands Francis V. O’Connor, a stately Old World-style connoisseur with a Vandyke beard and curled mustache, who believes erudition and a practiced eye are essential to judging authenticity. Mr. O’Connor, a co-editor of the definitive Pollock catalog and a member of the now-disbanded Pollock-Krasner Foundation authentication committee, said “Red, Black and Silver” does not look like a Pollock.

“I don’t think there’s a Pollock expert in world that would look at that painting and agree it was a Pollock,” Mr. O’Connor said at a symposium this month.

On the other side is Nicholas D. K. Petraco, a retired New York City detective and forensics specialist who examined the painting at the request of the Kligman estate. Approaching the canvas board as if it were a body at a crime scene, Mr. Petraco said he had no doubt the painting was made at the Pollock house and is linked to Pollock.

“I’ve had cases with less materials than this where people are spending 25 to 30 years in jail,” he said.

As technology advances, the art world has turned to microscopic analysis and pigment testing to buttress — or challenge — the judgments of a tiny club of experts whose opinions have long been treated as law. This pursuit of scientific validation has only deepened as art historians and institutions like the Pollock-Krasner Foundation, which shut down its authentication board in 1996, retreat from certifying art for fear of being sued.